Circuit breaker employing opposed fluid blasts



April 1, 1958 J. M. RAMRATH CIRCUIT BREAKER EMPLOYING OPPOSED FLUID BLASTS FiledJan. 17, 1956 (llRlCUliT BREAKER EMPiQYKNG GPPOSED FLUID BLASTS Joseph M. Rarnrath, Boston, Mass, assignor to Allis Chalmers.Manufacturing (Iompany, Milwaukee, Wis.

Application .lanuary 17, 1956, Serial No. 559,674

8 Claims. (Cl. 200-148) This invention relates to circuit interrupting devices and more particularly to arc extinguishing means for use in connection therewith.

in the construction and operation of circuit interrupters, it is frequently necessary to provide means for extinguishing quickly the are which is drawn between separable arcing contacts. This arc is usually blown by blowout means, such as an air blast, into an arc chute which is arranged to quench the are by lengthening it, cooling it, or otherwise.

The interrupting capacity of a circuit breaker interrupter in a high voltage circuit depends to a great extent on the circuit characteristics relating to the rate of increase of recovery voltage when the current is interrupted. Although the breaker may be successful in interrupting the current momentarily, the recovery voltage across the interrupting gap may rapidly rise to such a value that arcing is reestablished before the breaker has sufliciently increased the dielectric strength of the gap. For interrupting higher currents under such conditions, it would be necessary to increase the pressure and the intensity of the gas blast. If it is impractical to increase the gas pressure, the size of the blast passage or the type of gas passage or passages may be varied to provide for greater gas volume or greater interrupting ability. Such changes, however, usually result in either a more expensive or larger breaker.

In accordance with the invention claimed a fluid blast circuit interrupter is provided comprising a source of fluid under pressure, separable arcing contacts for e."- tablishing an arc, a conduit for conveying a blast of fluid from the source adjacent the arcing contacts for extinguishing the are drawn upon separation of the arcing contacts and an arc chute mounted adjacent the arcing contacts for receiving the are at one end thereof and exhausting the are products at the other end thereof. A blast divider is mounted within the conduit for directing the blast of fluid into the arc in two opposing streams of fluid under pressure.

It is, therefore, one object of this invention to provide a new and improved arc extinguishing device.

Another object of this invention is to provide a new and improved arc extinguishing device in which an arc extinguishing blast of fluid under pressure is divided into two opposing streams.

A further object of this invention is to provide a new and improved arc extinguishing device in which an arc extinguishing blast of fluid is divided into two streams of fluid downstream of the arcing zone and are then directed through the arc in opposing streams in the arcing zone.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing in which:

Fig. 1 is a diagrammatic showing partly in cross section Patented Apr. 1, 1958 of a fluid blast circuit breaker employing the present invention;

Fig. 2 is a view in cross section of the embodiment illustrated in Fig. 1 taken along the line IIII; and

Fig. 3 is a cross sectional view of the embodiment illustrated in Fig. 1 taken along the line III-III.

The cross blast type air blast circuit breaker shown by way of example in Fig. 1 comprises relatively movable arcing contacts, such as fixed contact structure 7 of the finger type and a pivoted blade-like contact 8. The fixed contact structure may comprise a plurality of current carrying contacts and an arcing contact as is well known, and is electrically connected to one line terminal 9 of the breaker. The bladelike movable contact is connec'ted to the other line terminal 10. Although in general, circuit breakers of the type considered in Figs. 1, 2 and 3 are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure is shown in the drawings and the circuit breaker will be described in detail as if it were of the single pole unittype.

The movable contact 8 is suitably connected to an actuating mechanism (not shown) through a connecting rod 11 for operating the movable contact between closed and open circuit positions.

For the purpose of extinguishing the are formed between the contacts when a power circuit connected thereto is opened, an insulating arc extinguishing structure 12 is arranged with respect to the contacts so that the arc is drawn at the entrance of the structure directly opposite a gas blast supply conduit 13. The conduit 13 is suitably connected through a blast valve (not shown) to a source of compressed fluid, such as air, comprising for example a storage tank and compressor equipment (not shown).

The are extinguishing structure may, for example, define a double barrel arc chute 14 comprising a first blast passage 15 for interrupting relatively high currents and a second blast passage 16 spaced apart from passage 15 for interrupting relatively low currents.

In accordance with the invention claimed an insulating blast divider 19 is arranged within the fluid supply conduit 13 for distributing the blast from the point where it arrives in highly concentrated form in the supply conduit 13 to an arc chamber provided for enclosing the are upon inception thereof. The are chamber comprises a plurality of arc splitter plates 20 set transversely to the longitudinal axis of the arc downstream from the arcing contacts. As the arc lengthens, it is bent around the arc splitter or cutter plates 20 and pushed by the force of the fluid blast into the narrow passages between plates 20 where it loses thermal energy by the cooling effect of the side walls and the decomposition of the plates themselves which produces arc quenching gases.

The blast divider 19 comprises a U-shaped streamlined structure having leg members 22 and 23 interconnected by a bight 24. The leg members 22 and 23 are so arranged that they substantially surround or envelop the movable arcing contact 8 as it passes through conduit 13 during a circuit opening operation. The legs 22 and 23 of the blast divider are arranged to extend longitudinally of the longitudinal axis of conduit 13 with their loose leg ends arranged adjacent the arcing zone. The bight 24 of blast divider 19 is provided with a fluid passageway 25 which extends longitudinally of conduit 13. Passageway 25 conducts a part of the blast of fluid flowing through conduit 13 through the blast divider 19 between leg members 22 and 23 and around the movable arcing contact 8. Blast divider 19 may be positioned immediately below a nozzle 26 formed in conduit 13 within the arcing zone. As shown in Fig. 2 blast. divider 19 is coaxially arranged within conduit 13 and so positioned therein that it divides the blast of fluid flowing through conduit 13 downstream from the arcing zone in at least least two streams of fluid and directs the streams through the arc and arcing zone in opposing or opposite directions. The leg members of the blast divider 19, as illustrated in Fig. 2, define a passageway 27 therebetween which accommodates the movable sickle-shaped blade contact 8 and controls the escape of compressed air and are products through passage 27 into blast passages 15 and 16.

A probe electrode 28 consisting of, for example, a tungsten alloy may be mounted at right angles to the arc path on the downstream side of nozzle 26. Electrode 28 which may be of a round form for aerodynamic reasons is connected to a damping resistor 29 of low ohmic value arranged on the outside of the interrupting chamber. One end of resistor 29 is connected to the fixed arcing contact structure 7 and the other end thereof is connected to the electrode 28. When the arc is blown against electrode 28 the arc current is conducted through resistor 29 thereby retarding the recovery voltage of the arc and increasing the interrupting ability of the device, as well known in the art.

As noted from the drawing and the streamlined shape of the blast divider, the blast air is conducted on its way to the arc zone with the least amount of turbulence but with a maximum of turbulence in the arc zone itself. Blast divider 19 envelops the moving blade 3 and seals the blast air from the stationary finger contact structure. The turbulence in the arcing zone is achieved by directing the blast air into the arc zone in two opposing streams. The are is drawn in the clashing zone of these two streams thus causing a maximum of turbulence at the zone of arc initiation.

The blast air before entering the arc zone should contain a minimum amount of free ions and electrons. By bringing the air into the arc zone in two streams around the streamlined blade envelope, irradiation by the arc is effectively shielded off and thus thermionization and photon formation is avoided and fresh uncontaminated blast air assured.

If arc interruption has occurred at an early current zero, a high degree of dielectric strength must be established immediately by the air blast in the arc zone and are products must be not allowed to contaminate this dielectric field by their presence but must be carried away rapidly. By drawing the arc in the downstream side of an expansion nozzle, the gaseous conductors are carried out into the cooling structure with ease and great speed thus maintaining the dielectric strength of the arc zone and eflectively preventing restiikes due to the rapid rise of the recovery voltage.

The air blast should attack the are suddenly and with great vehemence at an early stage after its inception to reduce buildup of arc energy. This is accomplished by having the blade 8 bottle up the entire escape area of the nozzle 26 until the arc is formed. At this moment a small area of nozzle 26 is opened up by blade 8 and the compressed air pounces suddenly and with great force onto the incipient arc. The are is acted upon by the air blast progressively as the blade uncovers more and more of the nozzle area.

The are should be forced into narrow passages for fast deionization. In this device a number of arc splitter plates 20 are set at right angles to the arc in the downstream side of nozzle 26. The arc, being transferred from the arcing fingers to a tungsten alloy arc runner 21, is made to climb up into the expansion side of nozzle 26. As the arc lengthens, it is bent around the arc cutter plates 20 and is pushed into the narrowpassages between the cutter plates 20 where it loses much of its thermal'energy by the cooling and decomposition eflect of the plates.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc comprising a movable arcing contact and a relatively stationary arcing contact, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, said conduit defining a passageway therethrough for said movable arcing contact, an arc chute mounted adjacent said contacts for receiving the are at one end thereof and exhausting the are products at the other end, and a blast divider mounted within said conduit and surrounding at least a part of said passageway for dividing and directing the blast of fluid flowing through said conduit into the arc in two opposing streams of fluid under pressure.

2. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc comprising a movable arcing contact and a relatively stationary arcing contact, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, said conduit defining a passageway therethrough for said movable arcing contact, an arc chute mounted adjacent said contacts for receiving the are at one end thereof and exhausting the are products at the other end, and a blast divider mounted within said conduit and extending from a point upstream of said movable contact substantially around said passageway, said divider dividing the blast of fluid under pressure upstream of said passageway into at least two streams of fluid and directing said streams of fluid through the arc in opposing directions.

3. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc comprising a relatively movable arcing contact and a relatively stationary arcing contact, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, said conduit defining a passageway therethrough for said movable arcing contact, an arc chute mounted adjacent said contacts for receiving the arc at one end thereof and exhausting the are products at the other end, and a U-shaped insulating blast divider mounted within said conduit for directing the blast of fluid into the arc in two opposing streams of fluid under pressure, said divider comprising a pair of legs and a bight, said legs substantially surround said movable arcing contact as it moves through said conduit and said bight defining a passage for a stream of fluid through said divider and around said movable arcing contact.

4. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable contacts for establishing an arc comprising a movable arcing contact and a relatively stationary arcing contact, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, said conduit defining a passageway therethrough for said movable arcing contact, said movable contact when in contact engaging position completely blocking said conduit and when moved to contact open position opening said conduit, an arc chute mounted adjacent said contacts for receiving the arc at one end thereof and exhausting the are products at the other end, and a blast divider mounted within said conduit tor'dividing the blast of fluid under pressure into at least two streams and directing said streams through the arc in opposing directions.

5. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable contacts for establishing an arc comprising a movable arcing contact and a relatively stationary arcing contact, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, said conduit defining a passageway therethrough for said movable arcing contact, said movable contact when in contact engaging position completely blocking said conduit and when moved to contact open position opening said conduit, an arc chute mounted adjacent said contacts for receiving the are at one end thereof and exhausting the are products at the other end, and a U-shaped insulating blast divider mounted Within said conduit for directing the blast of fluid into the arc in two opposing streams of fluid under pressure, said divider comprising a pair of legs interconnected by a bight, said legs substantially surrounding said movable contact as it moves through said conduit.

6. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, a movable arcing contact, a relatively stationary arcing contact for cooperating with said movable contact for establishing an arc, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, an arc chute mounted adjacent said contacts for receiving the are at one end thereof and exhausting the are products at the other end, a U-shaped insulating blast divider mounted within said conduit for directing the blast of fluid into the arc in two opposing streams of fluid under pressure, said divider comprising a pair of legs and a bight, said legs substantially surrounding said movable arcing contact as it moves through said conduit and said bight defining a passage for a stream of fluid through said divider and around said movable arcing contact, a probe electrode mounted adjacent said arcing contacts, and a resistor connected at one end thereof to said probe electrode and at the other end thereof to one of said contacts for retarding the recovery voltage of said interrupter during an interrupting operation.

7. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc comprising a movable arcing contact and a relatively stationary arcing contact, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, said conduit defining a nozzle adjacent said arcing contacts for directing high intensity streams of fluid under pressure into assaaai 6 the are, an arc chute mounted adjacent said contacts for receiving the are at one end thereof and exhausting the are products at the other end, a U-shaped insulating blast divider mounted Within said conduit for directing the blast of fluid into the arc in two opposing streams of fluid under pressure, said divider comprising a pair of legs and a bight, said legs substantially surrounding said movable arcing contact as it moves through said conduitand said bight defining a passage for a stream of fluid through said divider and around said movable arcing contact, a probe electrode mounted adjacent said arcing contacts, and a resistor connected at one end thereof to said probe electrode and at the other end thereof to one of said contacts for retarding the recovery voltage of said interrupter during an interrupting operation.

8. in a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc comprising a movable arcing contact and a relatively stationary arcing contact, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, said conduit defining a nozzle adjacent said arcing contacts for directing high intensity streams of fluid under pressure into the arc, a plurality of spaced splitter plates mounted adjacent said contacts for receiving the are at one end thereof and exhausting the are products at the other end, a U-shaped insulating blast divider mounted within said conduit for directing the blast of fluid into the arc in two opposing streams of fluid under pressure, said divider comprising a pair of legs and a bight, said legs substantially surrounding said movable arcing contact as it moves through said conduit and said bight defining a passage for a stream of fluid through said divider and around said movable arcing contact, a probe electrode mounted adjacent said areing contacts between said splitter plates, and a resistor connected at one end thereof to said probe electrode and at the other end thereof to one of said contacts for retarding the recovery voltage of said interrupter during an interrupting operation.

References Cited in the file of this patent UNITED STATES PATENTS 2,284,658 Hobson June 2, 1942 2,284,684 Prince June 2, 1942 2,284,857 Bennett June 2, 1942 2,297,818 Van Sickle Oct. 6, 1942 2,604,564 Jansson July 22, 1952 2,614,193 Cremer Oct. 14, 1952 2,678,984 Ramrath May 18, 1954 

